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Fascia Problem

JeffLianza

Hi Ziva Team, I'm sorry if this is an old issue or a silly problem. But I've been working on my fascia for almost 2 weeks now and it's driving me crazy. I've posted the issue two days ago but I took it down after an hour and decided to give it another try. But unfortunately it's really not working for me.

My issue is the fascia seems to be sliding with my zBones during sim, and the front legs seems to be merging together even if there are no accidental attachments on either of the legs. The fascia will eventually falls down, but by looking at the sim there are actually collisions.

I slowly followed Andy's video and documentations and checking Mr. Ink's scene files as well. I know I am doing something wrong or maybe its too technical for me to solve it, any help would be so much appreciated.

andy_vs

Hey Jeff,

You'll need a higher resolution tet mesh. At the moment the tets are spanning across the legs effectively welding them together.

Try some smaller values in the zTet size until the tets don't web across any longer. You'll probably want to get the resolution higher anyway in order to represent the shifting shapes of the underlying anatomy.

You can also vary the resolution of the tet mesh spatially by painting the zTet weights.

Also if your default pose has the legs just too close together, it would be best to change the default pose so the limbs are far enough apart so that you don't have to go very high on your tet resolution in order for them to separate.

JeffLianza

andy_vs Hi Andy, thanks for the tips. I will try it right away. cheers!

JeffLianza

@andy_vs Hi Andy, I've managed to get a it work and I am happy with the result. But I have this problem where the mesh seems to be getting sucked in the scapula area on both sides.

I tried adding attachments to the deltoids, Brachiocephalicus, Omotranseversarius and the scapula to see if it fixes it but its still there and I've checked my underlying objects if there are holes but there isn't. Any idea what's causing these weird deformations?

Im also having some weird shapes like the mesh are sticking together near the pectoralis area, are these the same issue wehere my Tets are too close with each other? I've made my resolution lower and finer, currently on 1.

Current setting is:

Thank you very much!

Jeff

andy_vs

That'll be a self-intersection on one of the underlying muscles 🙂

As soon as you have a self-intersection, you're opening up the door to incorrect projection results from the collision model.

If you go to a frame that is problematic, select all the muscles and bones, and run Ziva Tools > Find Self Intersections, my guess is you'll find some around the scapula that would be causing that issue.

JeffLianza

@andy_vs Hi Andy, I'm sorry for the trouble, I'm kinda stucked. I have another question now regarding the skin, I've seen most of the videos only talks about the fascia which doesn't have the head and the feet. Although I saw one thread about 8 days ago and James explained it sequentially but unfortunately I'm kind of confused about the whole process. My question is do I need to animate the skin (full body with head and feet) and point cache it so it will follow the head movement of my character? because from what I understand is the only part of the whole body that will be paint weighted was the one with the simulated fascia(point cache) which will obviously be followed the the skin, but since the head has nothing to attached to it means it has to be animated as well?

I hope you get my question somehow, or if there is any link you can point me to I would be grateful. Thank you so much.

Jeff

andy_vs

Hey Jeff, it's a common question, we need to be better at having resources on this step.
Here's an overview of a typical pipeline:

So yes you blend the area that is simulated back to the original animation rig.
It's really super simple to do the blend.
Just wrap a copy of your skin mesh to the skin simulation results, and make a blendshape between that and your animation skin. Paint the blendshape weights where you want the transition to be

andy_vs

As a further note, when you're making your animation rig, you don't really have to worry too much about the skin weights for the body, as you'll be using the sim results for this area anyway. You'd just concentrate on getting the hands, feet and face right.

JeffLianza

andy_vs Ahhh that's what I was thinking since the head movement is the only thing will be blended with the body skin sim. Thanks a lot! everything seems clear for now. Hoping not to run into some huge problems. Cheers!

JeffLianza

@andy_vs Thank yo so much Andy! I'll give it a try. Still fixing some small issues with the fascia, that weird depression going on with the shoulders are still there but not as bad as the first sim. I did fixed all the intersections but I'm still having some tiny dimples.

andy_vs

You're welcome!
So have you got some sliding attachments in there to help with the fat sim?
What I do is use the select by proximity tool to select the vertices that are directly adjacent between the muscle and the inside of the fat.
Always make the muscle object the source of the sliding attachment when doing skin.
Those sliding attachments shouldn't need to go higher than 107. Somewhere between 105 and 107 is a good range.

Hope that helps

JeffLianza

I started doing the the skin just to test it out but it seems that I'm doing something wrong. I know it should be simple and straight forward but I still have some questions on the proper steps I need to do.

From what I understand is this.

I have my Skin Geo full with head and feet (not animated) and another Skin Geo Alembic (with the head and feet moving).

On a new scene I have imported my fascia (alembic) together with the Skin Geo and Skin geo alembic.

Now my problem is whenever I wrap my skin geo to my fascia sim it doesnt move at all, even tho I already removed the paint weight of the blend shape to the area of the body that was wrapped.

I tried the next method where I converted the fascia sim to zBones and the Skin Geo (not animated) to zCloth. I blend shaped my Skin Geo alembic (animated to my zCloth and only paint weighted the head and feet so it will only follows the blend shape. My problem now is the fascia and the skin is falling down from my scene. and the rest of the Geo Skin is drooping down and not holding on the bones even when collision is on. When I applied pressure on zCloth the skin just flies away and explodes except for the head and feet. I dont know what Im doing wrong.

I tried following @jamesj reply on one of the threads (one with a nice illustrations) were he mentioned about 3 copies of geo with head and feet. I tried my best to follow as slowly as I can but maybe I'm too noob to understand it so it didn't worked.

Thank you for your patience, I know this might be irritating but I can't find any answers elsewhere.

Also, do you have any training programs that I can attend to, I wanted to introduce this to the school where I'm teaching but I have to make sure I can present a solid product and atleast understand it more so its easier for me to promote it to my boss.

Thank you very much.

Cheers!
Jeff

JeffLianza

Its alright I think I got it. I digged through the threads about skin and luckily found something that is more comprehensive for me. Now my only question is what is the best parameter setup for the zcloth, do we need to key and apply pressure again? or rest scale? Mine is folding so much even my bend stiffness is at .1

andy_vs

Glad you got it sorted!
No need to apply pressure on the zCloth or anything unless you want to try for some effect. I usually start with an attachment strength of 105. I find the default attrs serve me quite well for cloth. You can always smooth out unwanted wrinkling with a deltaMush 😮

JeffLianza

@andy_vs
Hi Andy, I started adding wrinkles on the skin. The skin was a duplicate of my fascia but without the thickness and doubled the subdivision level. I made the fascia sim alembic a zBone then the skin mesh a zCloth. I browsed through some old threads and found something you suggested. Having one attachment by selecting the fascia first then the skin and set the stiffness to 106, that having a higher stiffness value will result a finer wrinkles, then the cloth is as default. But when I tried I didn't get any wrinkles at all if there was it's very subtle. I did tried experimenting with different values but it wasn't successful. Since I only want some fine wrinkles on some parts I did tried to add another material and attachment to those parts.

But still doesn't work. Any advise on how can I get some nice wrinkles on a specific area like the image below?

Those are sliding attachment with a material too, I set the bend stiffness to 0.1 with 108 exp still didn't give me a wrinkle that I want.

This was actually the second try I did, the first one was instead of having one attachment I attached the wrists and the neck then made some sliding attachments on the obliques and lats, I did get a wrinkle but it's all over the place.

I find the second method works for me I just need to figure out how to add wrinkles on specific areas.
Thanks a lot for your time.

Jeff

JeffLianza

Sorry, I luckily figured it out... Did a lot of different testing and it came out to what I wanted. 🙂

andy_vs

JeffLianza

Hi Andy, here's my latest skin simulation. I've made one attachment with 105 stiffness with my material bend stiffness at 3 108. I also added a sliding attachment on some parts with 103 stiffness. I have added another material layer for pressure on parts where it started losing volume, and lastly a deltaMush to smoothen the wrinkles.

I'm quite happy with the result, the lumpiness of the skin was intended to match my lion heads details, I wanted to make it looked more ripped with almost 5 percent fats.

Thank you so much for the guidance and help, I really appreciate it. I will definitely post my future projects here.

Chers!

Jeff

Work in progress

andy_vs

wow!! it came out great! congratulations, was fun watching this project unfold